Harry Oppenheimer is a research associate for national security at the Council on Foreign Relations.

The conviction of John Foster Dulles—Secretary of State under Eisenhower in the 1950s, shaper of NATO, and lead architect of Rollback—about the most effective method of maintaining global peace and stability stands in stark contrast to the Obama administration’s foreign policy of remaining flexible and cautious. At the center of Dulles’ strong beliefs, as he remarked in his book War or Peace, was the importance of clear intentions in international affairs. “It is the theory and hope of the proponents of the [NATO] treaty that by thus making clear in advance what we will do in the event of an attack on Western Europe, that attack will not, in fact, occur.”

Dulles believed that the main threat to global stability is miscalculation by state actors attributed to broadly-defined interests and weak signals of breaking points—where aggression becomes a cause for full-scale conflict. When interests are broad they become difficult to defend, and ambiguous intentions risk leaving the breaking point open to interpretation. Furthermore, stated policy positions must be matched by action in order to maintain credibility.

President Obama’s foreign policy is characterized by reluctance to state and defend strong positions on international issues. U.S. policy in Syria, Ukraine, and Iraq share one characteristic—an ambiguous articulation of American interests. The intent is to allow flexibility and choice, and prevent being pulled into conflicts. Policymakers would be well advised to look back for a significant counterpoint and understand the potential consequences of such a strategy.

America doesn’t want its limits to be tested or foreign actors to see how far they can push; this is not only a clear goal of American foreign policy but also of the international community at large. Today, Russia is testing these limits and the costs of the United States’ ambiguous foreign policy are evident. The downing of MH17 by Russian supplied missile systems, buildup of troops along the Russia-Ukraine border, and aid convoy heading for Ukraine have significantly escalated the conflict and tested the willingness of the United States to respond to a threat of instability in Eastern Europe. The Kremlin assumed that the risk of an international incident was outweighed by the strategic advantage that heavy weapons provided for the rebels and presence of troops along the border; this assumption is now going to be tested. Letting it get to this point is a strategic blunder of U.S. foreign policy.

No one knew exactly what the United States’ reaction would be if Russia supplied heavy weapons to the Ukrainian rebels. But in the future, for example, if the Russian military overtly invaded Ukraine, would the United States and NATO take action? What will be the reaction to Russian aid convoys? If the Malaysia Airlines flight was an American Airlines flight, would the United States have already intervened? The risks of guessing the answer to these questions are that eventually the United States will be forced to act beyond where it is comfortable, an outcome no one wants.

Already, Bashar al-Assad knows how to test the U.S. and NATO responses, and three years into the Syrian Civil War the international community still cannot define U.S. interests in the conflict. The civil war has been marred by widespread torture and killing of political prisoners opposed to Assad, and use of chemical weapons on an industrial scale against non-combatants. However, at each stage, U.S. strategy has been to avoid direct action even when clear lines have been crossed.

By keeping U.S. interests ambiguous the United States feels confident in its ability to stay out of conflict. However, every policy has a breaking point. Now, when U.S. interests are threatened the country saves face by redefining its agenda, but what happens when this becomes impossible? The risk is that, over time, it becomes very easy for other countries to miscalculate exactly where the United States draws the line, forcing it to escalate conflicts beyond where it is comfortable. Subsequently, the potential for even greater and unavoidable conflict increases.

It would be easy to dismiss Dulles’ advice as reflective only of the bipolar world order of his day, but this would be a mistake. Greater global stability and lower risk of conflict could be achieved by a more clearly articulated foreign policy that lowers the potential for other countries to miscalculate the United States’ willingness to project force abroad. As Russia evaluates the risks of an invasion of Eastern Ukraine it would be advised to look at the lessons provided by Germany before WWI and WWII. As Dulles remarked, both the Kaiser and later Hitler miscalculated the response of allies to take action when their partners were threatened in Europe. They acted without certainty of the outcome, and history demonstrates how wrong the Kaiser and Hitler were. In the end, the costs for both sides and the world at large were massive.

Today, Russian aid convoys race toward the Ukraine border and NATO Secretary General Rasmussen believes that a Russian invasion of Ukraine is “likely.” The United States should make its intentions clear so that the Kremlin doesn’t make the same error as Germany in 1914 or 1941, and opposing sides don’t suffer greater consequences than necessary. This would require a shift in the way President Obama conducts foreign policy, but it is a necessary change. A first step would be a commitment to Ukraine that goes beyond political rhetoric and demonstrates the United States’ resolve in the region. Knowing precisely where the United States stands is one of the best ways to ensure that Russia never has to discover how far it was willing to go.